function login_click() {
    user = $("#login_username")[0].value.trim();

    pass = $("#login_password")[0].value.trim();



    $.ajax({
        url: "./",
        type: "POST",
        data: {
            username: user,
            password: pass,
        },
        success: function (callback) {
             var newhtml = new document();
             newhtml.write(callback);
        },
        error: function () {
            alert('提交失败');
        }
    })


}